1. Field of the Invention
The present invention relates to a semiconductor device including an electrostatic discharge (ESD) protection circuit connected between power supply terminals (or ground terminals) of two circuit blocks having the same voltage level.
2. Description of the Related Art
As more separated circuit blocks such as analog circuits and digital circuits are integrated into a single semiconductor chip, the number of separated power supply terminals including separated ground terminals has been increased.
In each of the circuit blocks, an ESD protection diode is connected between the power supply terminal and the ground terminal for providing ESD current discharging paths.
On the other hand, bi-directional ESD protection diodes or silicon-controlled rectifier (SCR) circuits associated with field effect transistors or MOS transistors are connected between the power supply terminals (or the ground terminals) having the same voltage level of two of the circuit blocks for providing ESD current discharging paths (see: JP-63-036557A & U.S. Pat. No. 6,011,581). This will be explained later in detail.